The specific aims are to determine: 1) the biophysical properties of native GABA receptors (GABARs) from identified CNS neurons. Single channel properties will be characterized and a kinetic gating scheme developed for GABARs from each neuronal type; 2) the pharmacological regulation of native GABARs from identified CNS neurons; 3) the functional expression of recombinant GABAR subtypes into GABAR isoforms; 4) the biophysical properties of recombinant GABAR isoforms assembled from GABAR subtypes which have been shown to be coassembled in hippocampal dentate granule cells, pyramidal neurons, cerebellar granule cells, and Purkinje cells; 5) the pharmacological regulation of these.